Motor Housing With Integrated Gears

ABSTRACT

A motor housing with integrated gears includes a motor having a first shaft, the motor configured to actuate the first shaft, a dowel, the dowel rotatably coupled to the first shaft, an encoder configured to surround the dowel, the encoder being configured to measure an angular velocity of the first shaft, a gear system in meshed communication with the first shaft, and a second shaft in meshed communication with the gear system such that the motor is operable to transmit power to the second shaft. The housing further includes at least one seal, the seal located on the dowel between the first end and the second end of the dowel and creating a barrier such that the dowel is rotatable within the seal while preventing migration of lubricant on the at least one gear into the encoder.

TECHNICAL FIELD

The following summary and descriptions relate to motor housings withintegrated gears and methods for assembly.

BACKGROUND

Systems that employ electric motors for actuation typically use geartrains to convert speed and torque from a motor. Output shafts ofelectric motors often have relatively high speeds, but low torques. Geartrains may be configured for use with electric motors to convert thesehigh speeds and low torques into relatively lower speeds and highertorques.

A gear train may be contained in a gearbox that is separate from a motorhousing. The gearbox may be mounted to an output shaft of the motor. Anoutput shaft of the gearbox may be configured to attach to a givensystem in order to provide actuation in accordance with the speed andtorque capabilities of the motor and gearbox combination.

Instead of housing a gear train in a gearbox that is separate from amotor housing, the motor housing may be configured to contain a geartrain. Such a configuration may provide a greater power density whencompared to motors and gear trains with separate housings.

SUMMARY

A motor housing with integrated gears includes a motor having a firstshaft, the motor configured to actuate the first shaft, a dowel, thedowel rotatably coupled to the first shaft at a first end of the dowel,the dowel having a second end opposing said first end, an encoderconfigured to surround the second end of the dowel, the encoder beingconfigured to measure an angular velocity of the first shaft, a gearsystem in meshed communication with the first shaft, and a second shaftin meshed communication with the gear system such that the motor isoperable to transmit power to the second shaft. The housing furtherincludes at least one seal, the seal located on the dowel between thefirst end and the second end of the dowel and creating a barrier suchthat the dowel is rotatable within the seal while minimizing migrationof lubricant on the at least one gear into the encoder.

A motor housing assembly includes a parallel axis gear system includingat least one gear, a brushless DC motor configured to power an outputshaft, the output shaft including a first end that is in meshedcommunication with the gear system, and an opposing second end, thesecond end coupled to a dowel, a gear output shaft in meshedcommunication with the gear system, such that actuation of the motor isconfigured to provide motion to the gear output shaft. The assembly mayfurther include a sealant system configured to minimize the migration oflubricant from the gear system, the sealant system further comprising atleast one seal located on the dowel and configured to minimize migrationof lubricant along the dowel.

The integrated motor and drive assembly described herein is especiallyuseful in a battery powered, industrial robot. A high power density, lowfriction loss, and compact and small envelope are enabled by theconfiguration of the gears, seals, and other structures.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the following detailed description ofthe various embodiments of the application, will be better understoodwhen read in conjunction with the appended drawings. For the purposes ofillustrating the various embodiments of the disclosure, reference ismade to the drawings. It should be understood, however, that theapplication is not limited to the precise arrangements andinstrumentalities illustrated in the drawings, in which:

FIG. 1 is a top view of a motor housing with integrated gears;

FIG. 2 is a cross-sectional view of the motor housing with integratedgears shown in FIG. 1 in accordance with sectional line B shown in FIG.1;

FIG. 3 is a sectional view of the motor housing with integrated gearsshown in FIG. 1 in accordance with sectional line A shown in FIG. 1

FIG. 4 is a bottom view of the motor housing with integrated gears;

FIG. 5 is a side view of the motor housing with integrated gears;

FIG. 6 is a side view of the motor housing with integrated gears;

FIG. 7 is a side view of the motor housing with integrated gears;

FIG. 8 is a side view of the motor housing with integrated gears;

FIG. 9 is a top perspective view of the motor housing with integratedgears;

FIG. 10 is a bottom perspective view of the motor housing withintegrated gears;

FIG. 11 is bottom perspective view of the motor housing with integratedgears with portions cut away; and

FIG. 12 is an enlarged partial cross sectional perspective view of aseal shown in FIG. 2;

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIG. 1 depicts a top view of a motor and gear assembly 10. The assembly10 includes a motor housing 12 that is configured to contain a motor 14and an integrated gear system 20. Housing 12 has a housing body 11 thatdefines a cavity 12 a or multiple cavities 12 a. Cavity 12 a may beconsidered to be one main cavity, or individual portions of the spacedefined by the housing body 11 may each be considered interconnectedcavities 12 a. A top plate 13 and a bottom plate 15 may be configured tobe removeably attached to the housing body 11 to create or enclose atleast one sealed enclosures. Motor 14 and gear system 20 are shown inFIG. 2, which shows a cross-sectional view of motor and gear assembly 10along sectional line B of FIG. 1.

Motor and gear assembly 10 is configured to provide a maximum powerdensity of 1.04 watts/cubic inch (0.063 watts/cubic centimeter). Powerdensity is defined by power/enclosed volume. The embodiment shown has apeak power output of 297 watts and an approximate cubic volume of 285cubic inches. The motor and gear assembly has an overall width ofapproximately 9.72 inches, a height of approximately 5.4 inches, and anapproximate depth of 5.4 inches.

As shown in FIG. 2, motor 14 is an electric motor, in particular, a DCbrushless motor configured to have a torque constant of 0.083 Nm/A.Other embodiments may employ the use of different electric motors,including low profile electric motors with similar features. Motor 14 iscontrolled by a control system 100 that sends power to the motor through3 wires 105 a,b,c. Motor 14 includes a motor output shaft 16. In someembodiments, the motor output shaft 16 may be integral with a firstpinion 22 of the gear system 20.

The gear system 20 shown in FIG. 2 is a parallel axis gear system. Thefirst pinion 22 includes teeth 22 a that are configured to mate withteeth 24 a of a first gear 24. First gear 24 preferably is coupled to orformed integrally with a second pinion 26. Teeth 26 a of second pinion26 are configured to mate with teeth 28 a of second gear 28. Second gear28 preferably is configured to be coupled to a gear output shaft 30.Alternatively, second gear 28 may be formed integrally with gear outputshaft 30. Gear output shaft 30 may be coupled to a system (not shown)requiring actuation, such as a battery powered robot.

In operation, when control system 100 activates motor 14, motor outputshaft 16 rotates first pinion 22. First pinion 22 in turn rotates firstgear 24, which causes the rotation of second pinion 26. The rotation ofsecond pinion 26 drives the rotation of second gear 28, which in turncauses the rotation of the gear output shaft 30.

The configuration of the gear system 20 may be optimized to provideenhanced efficiency and noise reduction. For example, gear ratios may beoptimized to minimize watt usage for a given duty cycle. In this way,the gear system 20 may be configured to consume a minimum amount ofenergy for a given duty cycle dependent upon the type of motor 14 beingused. In the embodiment shown, average power consumption in accordancewith a given duty cycle is 136 watts.

Gear system 20 may further include bearings 32, 33, 34, 35, 36, 37distributed on the motor output shaft 16 and first pinion 22, along withthe gear output shaft 30, and second pinion 26, respectively. Bearings32, 33, 34, 35, 36, 37 provide radial and axial support to the gearsystem 20 during operation. Bearing 32 may be located on the motoroutput shaft 16, between the motor 14 and the first pinion 22. Bearing32 may be a 6004-ZZ bearing available from Schaeffler Technologies AG &Co. of Schweinfurt, Germany. Bearing 33 may be positioned at the bottomof the first pinion 22, secured within the bottom plate 15 of thehousing 12. Bearing 33 may be a 6202-ZZ bearing also available fromSchaeffler. Bearing 34 may be located on the top end of gear outputshaft 30, under the output encoder 120. Bearing 34 may be a 6007-ZZbearing also available from Schaeffler. Bearing 35 may be located nearthe bottom of the gear output shaft 30, within bottom plate 15 and aboveseal 66 of the sealant system 50. Bearing 34 may be a 6207-ZZ bearing,also available from Schaeffler. As show in FIG. 3, bearings 36, 37 arelocated on opposing ends of the second pinion 26. Bearings 36, 37 mayeach be 6202-ZZ, also available from Schaeffler.

The gear system 20 preferably includes a lubricant 40 that coats theteeth 22 a, 24 a, 26 a, 28 a, of the respective gears and pinions 22,24, 26, 28 in order to reduce friction as the gears and pinions rotate.Lubricant 40 preferably is a synthetic lubricating grease such asKlübersynth GE46-1200 available from Klüber Lubrication located inMunich, Germany. Alternatively, other types of lubricants may be used,such as other long life lubricants.

Control system 100 preferably controls actuation of the motor 14 andprovides feedback regarding the motion of the first pinion 22 based on amotor encoder 110, the motion of the gear output shaft 30 as measured atan output encoder 120, and the heat of the system as measured at athermal switch 130. As described above, the actuation of the motor 14,the control system 100 may be configured to power the motor 14 usingthree wires 105 a,b,c that connect to the motor 14.

Motor encoder 110 may be configured to measure the motion of the firstpinion 22 using a dowel pin 18 that is pressed into the first pinion 22and held in place by a set screw (not shown). In some embodiments, themotor encoder 110 may be a Low Profile Incremental Encoder such asRCML15-1024/4-5MM-5-1, available from Renco, part of HeidenhainCorporation of Schaumburg, Ill. A top part 18 a of the dowel pin 18 isconfigured to rotate within in a hub 112 of the motor encoder 110. Asthe first pinion 22 rotates, the top part 18 a of the dowel pin 18 alsorotates within the hub 112 of the motor encoder 110 at the same angularvelocity as the pinion 22. Motor encoder 110 measures the angularvelocity of the dowel pin 18 and sends this information to the controlsystem 100.

Output encoder 120 may be configured similarly to motor encoder 110 tomeasure the motion of the gear output shaft 30. Specifically, a dowelpin 38 may be pressed into gear output shaft 30 and held in place by aset screw (not shown). In some embodiments, the output encoder 120 maybe an Optical Kit Encoder E5-1024-197-NE-S-D-A-B, available from USDigital of Vancouver, Wash. A top part of the dowel pin 38 is configuredto rotate within a hub 122 of the output encoder 120. As the gear outputshaft 30 rotates, dowel pin 38 also rotates within the hub 122 of theoutput encoder at the same angular velocity as the gear output shaft 30.Output encoder 120 measures the angular velocity of the dowel pin 38 andsends this information to the control system 100.

Thermal switch 130 measures the temperature within the housing 12 at itslocation within the housing. Thermal switch 130 may be a Snap ActionThermostat such as FC-P2D-105C, available from Portage ElectricProducts, Inc. of Canton, Ohio. In the embodiment shown, thermal switch130 is located above the gear output shaft 30 and below the outputencoder 120. Thermal switch 130 connects to control system 100 to shutoff the motor if a given temperature limit is reached. For example, ifthe thermal switch indicates that the temperature is above 105° C., thecontrol system may be configured to stop the motor 14.

Cavity 12 a or series of cavities 12 a of the housing 12 are configuredto fit the motor 14 and the gear system 20. Housing 12 includes asealant system 50 that may be used to contain lubricant 40 within thehousing or within a portion of the housing. Sealant system 50 mayfurther be configured to minimize or prevent leakage of lubricant 40onto parts of the control system 100 that may be contained within thehousing 12. Sealant system 50 may also be configured to minimize orprevent water or moisture from entering the housing.

A first aspect of the sealant system 50 controls the distribution of thelubricant 40. For example, a seal 52 preferably is located on the dowelpin 18 (FIG. 2) to prevent or minimize lubricant 40 on or near the motoroutput shaft 16 from leaking to the first encoder, such that the dowelpin 18 is rotatable within the hub 112 of the motor encoder 110. In oneembodiment, seal 52 may be a 5×15×6TC seal in Buna-N or a 5×15×6TC-PL inTeflon, both available from Dichtomatik located in Shakopee, Minn.

In alternative embodiments (not shown in the Figures), a seal may belocated below the motor 14 and above the ball bearing 33 in order toprevent or minimize migration of grease 40 from the gear system 20 tothe motor encoder 110. The use of a seal around the motor output shaft16, instead of around the dowel 18, requires a seal that has a largersealing surface than seal 52 because the diameter of the motor outputshaft 16 is greater than the diameter of the dowel 18. The increasescontact area of this alternative seal configuration also increases thefriction within the system, decreasing the overall system efficiency. Inthis way, embodiments similar to that shown in FIG. 2, with the seal 52located on the dowel 18, optimize the sealing structure to minimizefriction and increase the efficiency of the motor and gear assembly 10.For example, in the embodiment shown, seal 52 creates approximately 0.75ounce inches of torque friction. By way of comparison, the alternativeseal configuration mounted on the output shaft 16 could createapproximately 5.5 ounce inches of torque friction.

Sealant system 50 may further comprise a seal 64 located around dowelpin 38, in between the hub 122 of the output encoder 120 and the gearoutput shaft 30 to prevent or minimize lubricant 40 on or near the gearoutput shaft 30 from leaking to the output encoder 120. Seal 64 may beidentical to seal 52 in structure and material. For example, a seal 64may be a 5×15×6TC seal in Buna-N or a 5×15×6TC-PL in Teflon fromDichtomatik.

FIG. 12 depicts an enlarged partial cross sectional perspective view ofseals 52, 64. Seals 52, 64 may each have a generally cylindrical ringshape that may include strategically placed cut-out sections thatprovide enhanced sealing surfaces. For example, seals 52, 64 may includean outer annular portion 54 connected to an inner annular portion 56 bya bottom portion 58. Outer annular portion 54, inner annular portion 56,and base portion 58 together define a seal recess 60 that providesflexibility of movement for the outer and inner annular portions 54, 56.The outer annular portion 54 has a tapered top portion 54 a and a flaredbottom portion 54 b that may be formed integrally with the base portion58. The bottom surface 58 a of the base portion 58 may define anannular-shaped recess 58 a. Base portion 58 may also be formedintegrally with inner annular portion 56 at a bottom portion 56 b of theinner annular portion 56. The bottom portion 56 b of the inner annularportion 56 may include an annular flange 62 that extends inwardly anddownwardly from the bottom portion 56 b of the inner annular portion 56.A top portion 56 a of the inner annular portion 56 may define asubstantially semicircular annular recess 56 d configured to fit asubstantially cylindrical annular ring 63 that may be configured toprovide structural support to the inner annular portion 56. Annular ring63 may be made of the same material or materials as the outer annularportion 54, inner annular portion 56, and base portion 58.Alternatively, annular ring 63 may be made of a different material ormaterials. In operation, dowel 18,38 contacts the seal 52,64 at theinner annular portion 56 of the seal 52, including flange 62. Thisconfiguration prevents or minimizes lubricant 40 from migrating up thedowel 18, away from the motor 14 and gear system 20, towards the hub112, 122 of the encoder 110, 120.

Seal system 50 may also include a seal 66 that is located around gearoutput shaft 30 to prevent or minimize lubricant 40 on or near the gearoutput shaft 30 from leaking out of the housing 12. Seal 66 may havesimilar structure to seals 52, 64 as described above and shown in detailin FIG. 3, but is not limited to said structure. In some embodiments,seal 66 may be a 32×62×7TC seal in Buna-N or a 32×62×7TC -PL in Teflon,available from Dichtomatik.

The positions and configurations of seals 52, 64, and 66, work in inconjunction with seals 68 and 70 to minimize or prevent leakage oflubricant 40 outside of housing 12. Specifically, seal 68 is insetwithin the housing body 11 and compressed between the housing body 11and the bottom plate 15 to minimize or prevent leakage of lubricant 40outside of the housing. Seal 70 is located around the motor 14 and, inconjunction with seals 52 and 64, further function to minimize orprevent leakage of lubricant 40 into the encoders 110, 120, as well asoutside of the housing 12.

The seal system 50 also functions to minimize or prevent water ormoisture from entering the housing 12. Seal 68 works in conjunction withtop plate gasket 76, grommet 78, and motor wire seal 80. Top plategasket 76 may be affixed to top plate 13 of the housing 12, such thatwhen top plate 13 is secured to the body 11 of the housing 12, thegasket 76 is compressed, minimizing or preventing water or moisture fromentering the housing 12. More particularly, gasket 76 minimizes orprevents water or moisture from contacting the encoders 110, 120 locatedwithin the housing.

Grommet 78 also minimizes or prevents water or moisture from enteringthe housing 12 through top plate 13. Grommet 78 also has at least onehole configured to fit one or more wires that connect at least one ofthe encoders 110, 120 and thermal switch 130 to the portion of thecontrol system located outside of the housing 12. Grommet 78 may be partnumber 13979, available from Minor Rubber Co., Inc. of Bloomfield, N.J.

Motor wire seal 80 minimizes or prevents water or moisture from enteringthe housing 12 in the area that the motor 14 connects to its wires 105a,b,c. As shown in FIG. 1, motor wire seal 80 includes a motor wireplate 82 that has a flat edge 82 a and an opposing arced edge 82 b. Flatedge 82 a and arced edge 82 b meet at two opposing rounded corners 82c,d. The size and shape of motor wire plate 82 are configured so thatthe plate fits within a recess 81 defined by the body 11 of the housing12. Recess 81 has an upper portion 81 a that is open to the space abovethe motor and gear assembly 10, and a lower portion 81 b that connectsthe upper portion 81 a to the portion of the housing cavity 12 a thatholds the motor 14. Lower portion 81 b may be a substantially similarshape to the upper portion 81 a, but may have an overall slightlysmaller perimeter when viewing the motor and gear assembly 10 from thetop as shown in FIG. 1.

Motor wire plate 82 defines two through holes 83 a,b near each of therounded corners 82 c,d. Through holes 83 a,b are each configured to fita threaded screw 86 a,b. The threaded screws 86 a,b each mate withrespective threaded bores (not shown) in the housing body 11 to secureand compress a plug 84 and its o-ring 88 within the housing 12. Plug 84has a top portion 84 a that is substantially symmetrical to the motorwire plate 82. The bottom portion 84 b may have a substantially similarshape as the motor wire plate 82 and top portion 84 a, but may have anoverall smaller perimeter from a top view perspective. Bottom portion 84b also defines a recess 85 around its perimeter configured to fit theo-ring 88. Bottom portion 84 b, with o-ring 88 positioned in its recess85 is configured to fit within lower portion 81 b of the recess 81.

Motor wire plate 82 and plug 84 are configured with a series of holesthat are each configured to surround parts of the wires 105 a,b,c in thearea of the seal 80. While the embodiment shown includes 3 holes foreach of the wires 105 a,b,c, motor wire plate 82 and plug 84 may beconfigured with a different number of holes. For example, motor wireplate 82 and plug 84 may each have one hole to hold all three wires.Alternatively, motor wire plate 82 and plug 84 may be configured to havemore than 3 holes to accommodate more than 3 wires. For example, motorwire plate 82 and plug 84 may have 5 holes, including 2 holes for eachof the wires from the two encoders 110, 120.

The forgoing descriptions are not intended to be limiting in terms ofits exact configuration. For example, it will be appreciated that themotor and gear system contemplated may be modified for differentapplications. Further, the housing may be configured differently inother embodiments. Other modifications may be made to improve systemefficiency or otherwise enhance performance when used in a given system.

What is claimed:
 1. A motor housing with integrated gears comprising: amotor including a first shaft, the motor configured to actuate the firstshaft; a dowel, the dowel rotatably coupled to the first shaft at afirst end of the dowel, the dowel having a second end opposing saidfirst end; an encoder configured to surround the second end of thedowel, the encoder being configured to measure an angular velocity ofthe first shaft; a gear system in meshed communication with the firstshaft; a second shaft in meshed communication with the gear system suchthat the motor is operable to transmit power to the second shaft; and atleast one seal, the seal located on the dowel between the first end andthe second end of the dowel and creating a barrier such that the dowelis rotatable within the seal while minimizing migration of lubricant onthe at least one gear into the encoder.
 2. The motor housing of claim 1,wherein the motor is a brushless DC motor.
 3. The motor housing of claim1, wherein the gear system includes at least one gear.
 4. The motorhousing of claim 1, wherein the gear system comprises at least twogears.
 5. The motor housing of claim 4, wherein the gear system is aparallel axis gear system.
 6. The motor housing of claim 1, wherein atleast one of the at least one seal is made of Teflon.
 7. The motorhousing of claim 1, further comprising lubricant, the lubricant being asynthetic lubricating grease.
 8. The motor housing of claim 7, whereinthe synthetic lubricating grease is Klübersynth grease.
 9. A motorhousing assembly comprising: a parallel axis gear system including atleast one gear; a brushless DC motor configured to power an outputshaft, the output shaft including a first end that is in meshedcommunication with the gear system, and an opposing second end, thesecond end coupled to a dowel; a gear output shaft in meshedcommunication with the gear system, such that actuation of the motor isconfigured to provide motion to the gear output shaft; and a sealantsystem configured to minimize the migration of lubricant from the gearsystem, the sealant system further comprising at least one seal locatedon the dowel and configured to minimize migration of lubricant along thedowel.
 10. The assembly of claim 9, further comprising an encoderconfigured to measure an angular velocity of the dowel.
 11. The assemblyof claim 9, wherein the gear system includes at least two gears and atleast one pinion.
 12. The assembly of claim 9, the sealant systemcomprises at least one seal made of Teflon.
 13. The assembly of claim 9,further comprising lubricant, the lubricant being a syntheticlubricating grease.
 14. The assembly of claim 13, wherein the syntheticlubricating grease is Klübersynth grease.